It is well-known that lubricating oil such as grease may be applied to electric products and machine parts as a member to which lubricating oil such as grease is applied. On the other hand, in a process of manufacturing electronic parts, liquid such as chemical may be applied to a member to be manufactured. A discharge apparatus is usually used to discharge an incompressible fluid material such as lubricating oil and liquid to an object. The discharge apparatus is arranged and used between a discharge nozzle and a container having a fluid material accommodated therein. In some conventional cases, a discharge apparatus may be provided with a solenoid valve for switching a flow path; however, since the discharge apparatus includes a member such as a solenoid valve, the discharge apparatus is heavy and complicated. For this reason, the conventional discharge apparatus uses a drive unit for movement in two axial directions of X and Y, or the conventional discharge apparatus is fixed to a mounting pedestal and the object is moved.
In some discharge apparatuses, a pump member is elastically deformed for pumping operation; however, the discharge apparatus of this type also has a complicated structure. A conventional discharge apparatus having a pump member which is elastically deformed, such as a diaphragm, is appropriate for the case where the discharge amount is relatively large, but it is difficult to control the discharge amount with high precision to apply a small amount of fluid material equal to or not more than 1 g to the member to which the fluid material is applied.
The application quantity of the fluid material to electric products or machine parts differ depending on a member to which the relevant fluid material is applied, and as described above, the application quantity of the fluid material may be equal to or not more than 1 g, but more fluid material may be applied.
In order to supply the fluid material, such as lubricating oil, to a dispenser with high precision, the inventor devised a discharge apparatus having a structure to fill a control flow path with fluid material from a container, and discharge the fluid material to the dispenser from the control flow path. For achieving such a discharge apparatus, the control flow path diverges from the guide flow path between a discharge nozzle and the container having the fluid material accommodated therein; therefore, a three-way valve is used as a flow path switching valve. Japanese Patent Laid-Open Publication No. 2002-147625 discloses a three-way valve for switching the flow path.
As disclosed in Japanese Patent Laid-Open Publication No. 2002-147625, in the three-way valve having a spherical valve element, since the valve element is moved along a guide groove formed in a valve case, the valve element moves over a long distance to perform an opening/closing operation in a port. For this reason, the three-way valve has a response lag between when the port should be opened/closed and when the valve element actually finishes opening or closing the port. Since this causes the liquid to drip from the discharge nozzle, it is necessary to suck it back, and since the amount of the liquid flowing through the flow path is large, it is difficult to guide the controlled amount of liquid (slight quantity) from a flow path to another flow path.
It is an object of the present invention to provide a flow path switching valve and a discharge control apparatus which can control the discharge amount of a fluid material such as grease with high precision without causing it to drip, or without the need to suck it back, and has excellent sealing property and responsibility.